This invention generally relates to a single-lens reflex optical view finder of an optical system, such as a television or video camera, movie camera or the like, and more particularly, the present invention relates to a device for reducing the amount of counter-light which enters into the view finder through its eyepiece.
In a single-lens reflex view finder used for video cameras, movie cameras or the like, a half-silvered mirror is provided to partially reflecting incident light from a photographic subject so that an image of the photographic subject can be seen through its eyepiece. However, counter-light is apt to enter the view finder from the eyepiece to be transmitted to the half-silvered mirror in a direction opposite to that of the objective light. The counter-light is thus reflected at the half-silvered mirror to be applied to an object glass system in which the counter-light is reflected back to the half-silvered mirror. Some of the counter-light rays applied from the object glass system to the half-silvered mirror propagate therethrough to be applied to a photosensitive surface of the television camera tube in the case of a video camera and to the film in the case of a movie camera. If the intensity of the counter-light is high, the counter-light transmitted to the camera tube or the film may result in the occurrence of flare phenomena, deteriorating picture quality.
In order to remove the disadvantage by counter-light from the eyepiece of the view finder, some conventional video cameras have a shutter in the light path of the view finder so that the shutter may be manually closed to block counter-light. Some other video cameras have a cap which can be manually engaged with the eyepiece to cover the same. However, it is troublesome to manipulate the shutter or to put the cap on the eyepiece each time the shooter removes his eye from the eyepiece. Furthermore, if the shooter peeps into the view finder in such a manner that his or her eye is not in contact with the eyepiece, counter-light has a chance to enter into the eyepiece through the gap between the shooter's face and the eyepiece.